Is it possible to convert a PCI-e x1 slot into an old PCI slot? If so, how?

  • Some additional information might help you make the best choice. What card are you trying to use in a pci-e slot? There may be a replacement or upgrade that your money would be better spent on.
    – Troggy
    Sep 25 '09 at 20:24

Well after a little digging around (which I guess i should have done first) the truth of the matter is, yes, there actually are. There are little cards that you can slip into the PCI-e x1 slot to convert it to a PCI slot. Why would anyone want to do this you ask? well, many companies still make products intended for PCI slots, not PCI-e. It was the graphics card companies that lead the rush twords PCI-e (and for some very valid reasons).

However, new interfaces take time to get accepted, besides, if an old standard works perfectly fine, development of the product to switch to a new standard would be extra costs.

Unfortunately most computer motherboard manufacturers seem to want to follow the rush twords new technology even when older technology still works fine. What i don't understand is why do computer motherboard manufactures even put PCI-e x1 card slots in their systems. At the moment, the only technology that uses PCI-e slots is either graphics cards, raid controllers, or USB2.0. As far as graphics cards go, the PCI-e x16 slot is a necessary advancement. However, no one buys raid controllers because most people who use it have raid chips inside their motherboards anyways, this goes the same with USB2.0.

So whats the point of having PCI-e x1, x4, and x8 slots if they are rarely used? Instead of a useless PCI-e x1 slot, why not put in a useful PCI slot insted?

PCI-e x1 to PCI converters:


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    They make Ethernet cards, wireless cards, adapters etc. also. There is much more out there than just graphics, raid, and usb.
    – Troggy
    Sep 25 '09 at 20:29
  • The reason mobo makers like PCIe 1.x slots is that they're cheaper to implement. They only need 18 pins vs 62 for a 32bit PCI slot. Fewer traces leads to simpler board layout, less EMI, and potentially fewer layers needed in the PCB itself (this is a big cost savings). Jan 25 '10 at 15:59
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    Also, "RAID" chips on motherboards are almost never real RAID--they're software fakeraid. Real RAID cards generally have backup batteries.
    – Broam
    Feb 19 '10 at 15:39
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    Plenty of reasons for PCIe x1. First is cost/complexity. PCI is parallel technology requiring 16 interconnects. Having a single PCI slot requires just as much "resources" as having 6 PCI slots. Given PCI is a dead end there is no reason to move EVERYTHING to PCIe and thus remove entire PCI subsystem from northbridge. PCIe 1x has plenty of bandwidth. The newest version has 500MB/s in each direction. Compare that to 133MB/s for "conventional PCI. Soundcard, entry level RAID, video capture cards, TV tuners, etc can all be easily supported by PCIe 1x. Aug 31 '11 at 3:41
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    They key reason from the manufacturer's point of view for provinding PCI-E 1x slots rather than PCI-E ones isn't the bandwidth (which is a significant difference) or the relative cheapness of the connector due to fewer pins and traces: they have to provide the modern standard for high bandwidth devices (GFX, RAID) and providing both PCI and PCI-E instead of just the variations on PCI-E is considerably more hassle/expense in board design especially when you are running close to your profit margin anyway as most consumer grade electronics lines do these days due to competition pressures. Dec 19 '11 at 11:03

No, this is not possible. I have never seen a product for that purpose and I am not sure how they could do it. Pci-e slots(not even the full size 16x versions, let alone a 1x) are not backwards compatible with pci.

Edit: People are finding solutions for this. I do however agree they are not that cheap, add complexity (drivers, overhead, etc), and some of these adapters I am seeing will only work with low profile cards. I know some of these adapters will not work with all cases. You might have to remove the case mount plate on the PCI card to be able to use. If it is a full height PCI card, you might be stuck in many cases, unless you do not mind the side of your case being off.

  • Motherboard expansion slots are designed to line the card up with the back of the case. So even if an adapter was somehow produced, I am not sure how they would fit an adapter and the card properly. None the less, good question.
    – Troggy
    Sep 25 '09 at 18:58
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    Yea, they are damn expensive...oh well at least I'm not paying for it. Ill probably get one of those quad box things, in case i need even more slots. This actually works out quite nice as i wont be needing those slots for quite some time, this means i can squeeze more money into the computer budget itself to get a more powerful computer and buy the converter box later as some other expense (i don't like it when the computer can't keep up with me)
    – Faken
    Sep 26 '09 at 18:24
  • There are PCI-E to PCI-X bridge chips, OCZ uses them in their RevoDrive and IBIS because they're very cheap. PCI-X is backwards compatible wit PCI, but so far risers aren't that widespread because PCI is almost extinct and you could only use a half-height card. Nov 11 '10 at 4:58

They do and they work. I bought a simple slim one that adds about 1" height to the MB PCI slot (Tekit Desktop PCI-E1X TO PCI expansion card available at Newegg.com) and use it for my extremely old but necessary PCI modem that supports nextalk TTY software for the deaf. That older modem is the only one that will work with the software in windows 7 & up (not tested in Windows 10). Fortunately I have 3 of the older modems and taking care to keep them operating normally for over 15 years now. Now I can upgrade to newer motherboards that rarely have PCI ports (considering upgrading to newer GIGABYTE GA-X170-EXTREME ECC (rev. 1.0) LGA 1151 Intel C236) to that I can take advantage of NVMe M.2 ports, etc.

What should be happening is that MB makers should be including adapters that do just this--plug it in to convert it to PCI or PCIex1, etc. IN other words--backwards compatibility just like USB 3.0, 2.0, etc.

If in the future Windows 10 won't work with the software I can always run Windows 7 in a virtual windows to make use of the modem. Already tried that and it works.


PCIe-to-PCI converters exist, but they are rather expensive and add another layer of complexity to a computer's setup.

It's generally cheaper to purchase a new expansion card that is PCIe rather than attempting to fiddle with a converter.


Assuming that you're actually trying to plug a PCIe card to your desktop...

Double check your motherboard's manual. Sometimes you can plug a PCIe x1 board to a slot that is PCIe but more lanes than x1.

If you're trying to plug a PCI card on to a PCIe slot, that's quite different. You can probably still find a PCI to PCIe bridge somewhere, but it's not worth your while.

  • this don't help much if he got a reqular PCI card Sep 25 '09 at 19:49
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    Yah, this doesn't answer any part of the question.
    – Troggy
    Sep 25 '09 at 20:14
  • I actually wrote that thinking that he wants to convert a PCIe card into a PCI. If that's the case, the OP could be just looking for the right slot to put his PCIe card. However, if he's looking for a PCIe slot, to convert to a PCI slot, then he's probably just out of PCI slots.
    – calyth
    Sep 25 '09 at 20:32
  • Actually, im trying to buy a powerful budget computer for use at the university. I found the exact PC i wanted at dell with a very reasonable price, the only problem is that it only comes with 1 PCI slot and a whole whack of PCI-e x1 and x4's which are total useless. We cant swap out the motherboard to get more PCI slots. Thats why i was looking for something like this so i can plug in more PCI slots. I'm doing some robotics control and i need 2 PCI slots for motor controler boards.
    – Faken
    Sep 26 '09 at 18:09
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    @Faken Last I read about hardware bridges were for graphics card, bridging a chipset in PCIe to AGP (or the other way around). It doesn't require drivers, but it introduce another item for things to cause problems. A 2 PCI slot board is abundant. And you shouldn't blow through your budget unless you're getting an i7. Is your program single-threaded? or multi-threaded? i.e. is it cranking at a tedious task that can't be broken apart? or is it busy juggling tasks?
    – calyth
    Oct 1 '09 at 20:32

Is it possible to convert a PCI-e x1 slot into an old PCI slot?

No. PCI-e slots are completely different from PCI slot. Different pin-outs, different signals, different protocols. Converting PCI-e to PCI is like converting an electrical wall outlet to deliver water.

What you can do is use a PCI-e card with a PCI bus on it. This is an active card which speaks the PCI-e protocol and rather than adding popular things like network, graphics, RAID, SAS, etc you add a PCI bus. Then connect the your PCI card to this bus.

That is quite a bit different from 'convering' it.


Such adapters exist, for example the Startech PEX1PCI1 but there are some caveats.

The data interface is handled by a PCIe to PCI bridge chip. This part is not a problem, PCIe to PCI bridge chips are used on many motherboards and expansion cards and they work just fine.

Where it gets messy is mechanical and power considerations. The adapter card with the bridge chip on has a finite non-zero height. In the case of the Startech one it's designed so that using the adapter in conjunction with a low-profile card results in a regular height card that works fine if you have a low profile card with a low profile bracket. If you have a low profile card but with a full height bracket you may find it difficult to securely mount the card. If the actual card is full height then you may find it is not possible to access the connectors on the backplate or that it is not possible to fit the lid on your case.

Then there is power. PCI slots need 5V but PCIe slots don't provide it, so you end up with a cable hanging off the adapter board that needs to be connected to the power supply.

Finally the adapters are quite pricey, presumably because they are a niche product.

Often replacing the motherboard or card is likely to be a better option. The good news is that since this question was asked most types of expansion cards have become available in PCIe x1.

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